赤道几内亚里奥穆尼盆地石油地质特征及勘探方向

Petroleum Geology and Exploration Directions in Rio Muni Basin,Equatorial Guinea

位于赤道几内亚的里奥穆尼盆地是裂谷盆地与被动大陆边缘盆地叠加的中—新生代复合型含油气盆地。盆地的构造演化经历了裂谷期、过渡期和漂移期三个阶段。盆地地层以过渡期盐岩层为界,盐下为裂谷期层序,盐上为漂移期层序。盆地生储盖组合可以划分为上、中、下三套,中组合最为有利。盐下裂谷期圈闭类型以断块圈闭和背斜圈闭为主,盐上漂移期以盐构造相关圈闭、地层圈闭和复合圈闭为主。盆地内油气成藏主要受盐构造、重力滑脱构造、断层和储层的控制。盆地中带的最有利勘探区带为盐构造发育区和重力滑脱区,盆地外带最有利的勘探区带为具有有效油源通道的有利圈闭和有效储层发育区。上白垩统桑托阶—坎佩尼阶—马斯特里赫特阶浊积砂岩是盆地当前最现实的勘探目标。

Rio Muni Basin in Equatorial Guinea is a Meso-Cenozoic sedimentary basin.The tectono-stratigraphic evolution of the basin is divided into a number of separate stages： the rifting stage（Neocomian through Mid-Aptian）,the transitional stage（Mid-Late Aptian） and the drifting stage（Albian through Late Tertiary）.Major source rocks are Late Aptian to Early Albian marine shales,and the proved reservoirs are Santonian and Campanian turbidites.Fault blocks and transpressional anticlines are main trap types during rifting phase whereas salt-related anticlines,stratigraphic traps and combination traps are main trap types during post-rifting phase.Salt-related structures,gravity glides and slumps,faults as well as reservoirs control hydrocarbon accumulation in Rio Muni Basin.The most favorable exploration areas are in the middle zone of the basin where salt-related structures,gravity glides and slumps are developed while the outer zone,the most favorable exploration areas are the ones which comprise favorable traps,effective reservoirs and good migration pathways.The Upper Cretaceous Santonian-Maastrichtian Turbidites are the most promising exploration targets.